← All status codes4xx – Client Error

HTTP 412 – Precondition Failed

One of the conditions in the request headers is not met by the server.

Common use case

Used with conditional requests like If-Match, to prevent a client from updating a resource that has changed since it last fetched it.

Example

HTTP/1.1 412 Precondition Failed

History

Part of HTTP/1.1 (RFC 2068, 1997).

Did you know?

It is the read-before-write safety net behind ETag-based optimistic concurrency control.

Other 4xx codes

400Bad Request401Unauthorized402Payment Required403Forbidden404Not Found405Method Not Allowed406Not Acceptable407Proxy Authentication Required408Request Timeout409Conflict410Gone411Length Required413Content Too Large414URI Too Long415Unsupported Media Type416Range Not Satisfiable417Expectation Failed418I'm a teapot422Unprocessable Content425Too Early426Upgrade Required428Precondition Required429Too Many Requests430Shopify Security Rejection431Request Header Fields Too Large444No Response451Unavailable For Legal Reasons460Client Closed Connection463Malformed X-Forwarded-For Header464Incompatible Protocol Versions494Request Header Too Large495SSL Certificate Error496SSL Certificate Required497HTTP Request Sent To HTTPS Port499Client Closed Request